Serotonylation of vascular proteins important to contraction

• Published in: PloS one 2009-05, Vol.4 (5), p.e5682
• Main Authors: Watts, Stephanie W, Priestley, Jessica R C, Thompson, Janice M
• Format: Article
• Language: English
• Subjects: Actin; Actins - metabolism; Amines; Analysis; Animals; Antibodies; Aorta; Aorta - enzymology; Arteries - metabolism; Biological effects; Biotin; Biotinylation; Blood Proteins - chemistry; Blood Proteins - metabolism; Cardiovascular Disorders/Vascular Biology; Contraction; Coronary vessels; Cytoskeleton; Enzymes; Glutamine; GTP-Binding Proteins - antagonists & inhibitors; Hypertension; Immunocytochemistry; Immunoglobulins; Immunoprecipitation; Mass spectrometry; Mass spectroscopy; Muscle contraction; Muscle Contraction - physiology; Muscle proteins; Muscle, Smooth, Vascular - metabolism; Myosin; Nitric oxide; Organ Specificity; Pharmacology; Physiological aspects; Physiology; Physiology/Cell Signaling; Proteins; Pulmonary arteries; Rats; Rats, Sprague-Dawley; Receptor, Serotonin, 5-HT2A - metabolism; Receptors; Rodents; Serotonin; Serotonin - metabolism; Serotonin receptors; Smooth muscle; Tandem Mass Spectrometry; Time Factors; Toxicology; Transglutaminase 2; Transglutaminases - antagonists & inhibitors; Trends; Vascular tissue; Veins & arteries
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0005682

Serotonin (5-hydroxytryptamine, 5-HT) was named for its source (sero-) and ability to modify smooth muscle tone (tonin). The biological effects of 5-HT are believed to be carried out by stimulation of serotonin receptors at the plasma membrane. Serotonin has recently been shown to be synthesized in vascular smooth muscle and taken up from external sources, placing 5-HT inside the cell. The enzyme transglutaminase uses primary amines such as 5-HT to covalently modify proteins on glutamine residues. We tested the hypothesis that 5-HT is a substrate for transglutaminase in arterial vascular smooth muscle, with protein serotonylation having physiological function. The model was the rat aorta and cultured aortic smooth muscle cells. Western analysis demonstrated that transglutaminase II was present in vascular tissue, and transglutaminase activity was observed as a cystamine-inhibitable incorporation of the free amine pentylamine-biotin into arterial proteins. Serotonin-biotin was incorporated into alpha-actin, beta-actin, gamma-actin, myosin heavy chain and filamin A as shown through tandem mass spectrometry. Using antibodies directed against biotin or 5-HT, immunoprecipitation and immunocytochemistry confirmed serotonylation of smooth muscle alpha-actin. Importantly, the alpha-actin-dependent process of arterial isometric contraction to 5-HT was reduced by cystamine. 5-HT covalently modifies proteins integral to contractility and the cytoskeleton. These findings suggest new mechanisms of action for 5-HT in vascular smooth muscle and consideration for intracellular effects of primary amines.